The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: 0116harley on 27.02. 2012 16:41
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Hi all, can any one help me on this one. Trying to a adjust my dynamo chain, but it keeps going really slack an then tight. The dynamo was rebuilt last year and i brought a new sprocket today, still the same. The only thing thats not bin changed is the chain, could it be this.
cheers Neil ????
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It seems that when tightening the dynamo securing bracket the dynamo turns slightly which results in a tight chain. Also the chain could be, sort of stretched on one side of the loop. If its too worn on one side then it needs changing otherwise find the tightest side by turning the engine over, then slacken the chain just a tiny amount and then tighten up dynamo bracket. Re check by turning engine over and when all seems good, grease up the chain. Remember when securing dynamo to push the dynamo up to the cork gasket against the timing side casing. *smile*
Edit: Just re read that... Hope its understandable.
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Bent armature shaft? Test for runout.
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This is a very common problem normally caused by the dished drive sprocket which is crudely made and often out of true. even if you've bought a new one it may not be particularly good. I suggest you mark the drive sprocket and see if the chain tightens every time the mark is in the same place. If it does this proves the chain tension is affected by the drive sprocket. If this is not the case you might try marking the chain and test again. If the tension is when the chain mark is in the same place then you have an unevenly worn chain - I doubt this to be honest. If the chain was worn unevenly there would be tension as the worn part was resting on the drive sprocket, then the chain would go slack as it is released from the sprocket. A lot of people are now using belt kits instead.
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That's a good answer Andrew... I never thought for one moment that the drive sprocket could be at fault.
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Thanks for that info beezamacc. Ill have a good look at things over the weekend. Like you say the way to go is a belt kit, but getting fed up with spending money on this bike, so gonna have to make do with what ive got.
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Thanks for that info beezamacc. Ill have a good look at things over the weekend. Like you say the way to go is a belt kit, but getting fed up with spending money on this bike, so gonna have to make do with what ive got.
I've got three used and mildly rusty, but useable drive sprockets that you can have for just the postage. You can try and find the best one and use that then!
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Thanks for that racerman, ive checked the new sprocket and it dont seem to bad. So gonna buy a new chain an hope that improves things
cheers Neil
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Do yourself a favour and get a belt conversion kit from Dynamo Regulators Ltd, Mike Huchings is the chap to have a chat with on 01489 880552 or go to www.dynamoregulators.com I fitted one of these to my Golden Flash and its the best money I've spent on the bike, quieter and a better charge at tickover. BTW I have no involvement in this company, I just found that this chap knows what he's talking about.
Kind regards TTJohn *smile* *smile*
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This relates to a couple of different topics, so may need to move or partially copy last paragraph??
I realized that the photos didn't add on so had another go.
I guess it's related,but I've a new Genny belt setup to add on that i was playing with today, and the large pulley (that goes on the idle gear) was interfering with the casting protrusion for the idler gear(IG) oil feed, debated with Self re: end float adjustment/move IG on shaft to suit,which would affect belt alignment, or remove material from casting(green bit) or inside corner of belt pulley(red bit). So I did both .
The( top green bit) is where it interferes with casting 28032012523 .jpg
Red bit is what interfered and I ground down 29032012524.jpg
Not to say that all will have same hassle, but as I say I debated with >Self < re: breather cork/inner cover gasket thickness, idler gear float(which I consider negatable except for>),pulley on taper positioning-important for alignment with genny pulley. Food for thought /feedback welcome. Jest holler->
Now too there's a sequel to this- When I tried to put the outer cover on, it wouldn't go- turned out the gen pulley was interfering with the bottom of the cover, as it protrudes further out than original, even though plenty clearance on inner cover, so I drew a 'dummy' gasket (see photo)of outer cover,in black, and super-imposed it over inner, and drew the inner cover mating surface in red and it can be seen the black outline crashes into pulley by about 1mm. and mating surfaces don't line up well.
This also can partially explain " oily right foot" as posted elsewhere!!!
To rectify this issue I needed to either:
1> move pulley inwards on idler shaft-not a good option due to above issue or,
2> find another cover, or
3> build bottom side of joint with ally weld and carve topside to suit,which I did(see bottom photo) and will do the weld later, to widen the mating surface, may as well as this cover is otherwise not good anyway, and no guarantee any other cover will be better.
So far so good,cover fits, now back to where I left off.
Oh yeah, I had a 'similar' issue with the inside of the oil pump pinion too, but will talk about that later elsewhere. Have a nice day, duTch
ps I tried to keep the photo resolution down but readable, hope it's ok?
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I had the same problem Dutch and used the same method to rectify it, also had to trim the gasket a bit but that's a matter of who supplies the gaskets some are much wider than they should be
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Hi everyone thought id sorted the problem with my dynamo chain going tight then slack . Not the case, riding home the other week strange noise coming from the timing cover. Good job i wasnt far from home,anyway took the cover of an found a tooth missing from the sprocket (new sprocket). Wasnt happy but the dealer replaced it with an other spocket. Same problem as before when fitted. Chain going really tight then slack , so ended up taking the iner cover of an bolting the sprocket to the timing gear. I found about a 4mm difference from one side of the spocket to the other.Now ended up fitting a old sprocket which seems runs ok.
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Yo B-Bill, it's heartening but not good that I'm not alone with that, after I get the show on the road again I'll look at widening that mating joint between the genny case and oil pump, and the gasket may as well be trimmed as it's doing nothing out there in space,'cept flapping on the G.sprocket/pulley, same as gouging the excess off the wrong side of casting s I did.
Harley , that's a lot of run-out, should be able to see that in situ though? Another thing I wonder is end float on the idler gear, and general chain/sprocket alignment ie, check that the cork gasket behind dynamo is ok thickness??
cheers duTch
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I would just like to add:
"not all dynamo belt drive kits are the same"
Our DRL kit has a chamfer on the inner side of the large pulley to avoid the casting. Also the steel flange is of a smaller diameter such that it will not foul the cases. Not only this but the drive ratio is 20% up on standard and the belt is 15 mm wide. Oh, and there are threaded holes to extract the large pulley.
But it is difficult with this sort of product to cater for all the worst case tolerances in the casting over the years of manufacture. But I have not heard of any problems with our kit fouling to date (fingers crossed)
Happy Tuesday
Mike
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I recently fitted one of Mike's belt drive kits to my 61' A10.
Very high quality piece of kit that fitted perfectly, everything you need is in the kit including a new gasket for the timing cover.
On my bike there is enough clearance between the drive (larger) pulley and the case to remove and refit the belt without removing the pulley.
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Hiya Mike and Brian,
I'll keep it in mind for next time I need one- could be a while, but no criticism of my belt/pulley product, the outer cover being the main offender.
Just as a reference my large pulley is 77mm overall dia, 10mm wide belt, 15mm wide overall. Small one, 32mm/15mm. Ratio, 46/17.
Cheers ,duTch